Child resistant safety closures comprising two nested closure members are well known in the art. Typically, the outer and inner closure members are provided with cooperating sets of lugs which engage each other when the outer closure is rotated in the direction to remove the closure. A plurality of spring fingers on the inner surface of the base wall of the outer closure member yieldingly urge the outer closure member away from the inner closure member. In U.S. Pat. No. 3,857,505, the outer surface of the base wall of the inner closure member is formed with a plurality of ramps and associated tear drop shaped detent projections which are associated with the plurality of spring fingers on the inner surface of the base wall of the outer closure member such that when the outer closure member is rotated relative to the inner closure member in a direction to apply the closure, the spring fingers engage between the ramps and the detent projections to orient the outer closure member circumferentially relative to the inner closure member to prevent inadvertent engagement of the lugs by any top load. When the outer closure member is rotated in the opposite or unthreading direction, the spring fingers ride over or slip over the detent projections. When the closure is rotated in the unthreading direction and an axial force is applied to the outer closure member the lugs are interengaged to unthread the inner closure member from the container.
It has been found that the use of lugs and detent projections on the inner closure member together with the spring fingers limits the number of lugs on the closure members because of the limited vertical space between the closure members. As a result, it is necessary to rotate the outer closure member through a larger arc, sometimes as much as 90.degree. to engage the lugs, necessitating grasping, releasing and regrasping the outer closure member.
Among the objectives of the present invention are to provide a child resistant closure which effectively holds the inner and outer closure members out of engagement thereby preventing top load from being applied during shipment of the containers to which the closures have been applied; which provides for a greater number of cooperating lugs; which has a lesser height; and which can be readily manufactured.
In accordance with the invention, a child resistant closure comprising outer and inner nested closure members each of which has a base wall on a peripheral skirt with sets of lugs on the inner surface of the outer closure member and on the outer surface of the inner closure member which are adapted to be engaged when the members are moved axially toward one another. The outer surface of the base wall of the inner closure member is provided with a plurality of ramps and depressions and the inner surface of the base wall of the outer closure member is formed with a plurality of integral spring fingers. When the closure is applied, the springs fingers engage the depressions and orient the outer closure member and inner closure member preventing inadvertent engagement of the lugs by any top load. When the outer closure member is rotated relative to the inner closure member without bring the lugs thereof into engagement, the spring fingers slip over the ramps allowing the outer closure member to rotate with respect to the inner closure member.